New L Drums: Inspection Report & Group Buy

Interests:Full time gunsmith who loves Thompsons, 35+ years experience.

Posted 22 December 2004 - 10:39 AM

Inspection

For the purposes of this report, “early drums” means WH & early Kahr production (apologies to the pre 1950's products)

A group of 7 new production Kahr L drums are involved in this study. These were NIB and unused. I feel a lot of this quantity is adequate to give a reasonable picture of what to expect from this production run.

A comprehensive inspection was not attempted, but several areas that have proven problematical with the early drums were examined, as well as areas generally considered “important”.

The Guide (spiral which directs the cartridges) in the Body is of singular importance in the function of the drum. If there are places where the cartridges cannot pass, the drum simply won’t work. In inspecting this feature, a gage is used which represents the minimum dimension given in the GI print. This Gage is larger than the maximum cartridge and if the guide will accept it, there will be no binding during operation. In some instances the guides would not gage and could not be adjusted to gage. In this case, free movement of actual cartridges was checked and is considered the sub minimal standard. Due to the expense of ammunition and time constraints, it was decided to adjust the guides as required prior to testing.

Of the 7 drums, only one would gage without adjustment, 2 could not be brought to gage, all passed cartridges freely. The adjustments made were more easily accomplished than in early drums.

The Cartridge Aperture refers to the slot in the top of the body through which the cartridge being fed into the gun is visible. This slot positions the round and keeps it in place. All of the samples are oversize by about .075. I consider this to be the major fault of this production. There are ways to address it and these include adding metal or moving the lip of the slot adjacent to the deflector to cause a V type of support for the cartridge. If the drum works in it’s current condition, then I guess it’s a moot point for now.

The Mounting Plates have proven to be a real problem in the early drums, most not fitting guns at all without some serious reforming. I am pleased to report that all measure OK (although the form isn’t quite up to the print) and fit a gun of known dimension with just the slightest drag in one place. I feel this will quickly abate with use, and fitting to an ‘in spec’ gun will not be a problem. One exception had the rear plate rivets only partially set, causing them to hit the frame. When reset, all was well. The opposite ends of those rivets, on all samples, are not properly formed and this causes the ratchet to “click” 12 times per revolution instead of 4. The heads of these rivets can be reset & trimmed to eliminate this trouble.

The Winding Key slot is about .005 small on all examples and will not work with most Pre 1950 drums. The Guard was bent down on 6 of the samples, which made lifting the latch difficult. This was easily straightened.

Metal Hardness specifications call for a soft, low carbon, mild steel that can be formed to the shapes necessary. I tested the hardness of the body of a WH, new Kahr and (choke) my Bridgeport. The results are as follows: HRB 53, 46, 54 respectively. The guides in the new Kahr appear to be softer than the GI parts.

Other Things noted were that the tail of the guide was not bent around at its end to indicate the area into which cartridges were not to be placed; you could actually get 54 rounds into the drum, but this is not recommended. I bent some of these in various ways, just playing.

The Rotor is formed in such a way as to not have as great a surface area pushing on the cartridge as the early drums had. I did not see any problem with this during bench testing, as long as the guides were spaced correctly.

Many parts have burrs on the edges.

Range Report

I took 6 drums to the range for firing in a 28 TSMG known for flawless function and cycling at a clocked rate of 740 RPM (the seventh drum was tested previously and function was fine). Firing was a continuous burst until the drum was empty, or stopped for some other reason.

Only one drum would not run, the others were flawless. The offending drum had been the most difficult to adjust in the initial inspection of the body and guides and was subsequently found to be suffering from a cover guide alignment problem as well as some slight drag of the rotor on the body. These flaws were corrected and I expect this drum will run fine during the next range outing.

The oversize cartridge aperture allows the top round to sit high enough to preclude the insertion of the loaded drum into the gun unless the cartridge is pressed into the magazine with a finger, allowing it to clear the magazine well of the receiver. This was easily accomplished, presenting no serious problem.

Summery

Overall, we see improvements in this new production run and feel good about the way the mags fit the guns and the ease with which the majority of the samples evaluated can be adjusted. The oversize cartridge aperture is the sour apple but doesn’t seem to affect function in the short run. Merle and I are in consultation as to how to effectively correct this condition, should a long run problem arise.

Group Buy; here’s the deal

If any of you guys want to proceed with a group buy, I am willing to facilitate the same.

No additional warranty. Please keep in mind that I will not warrant in any way the Kahr product as received, I will simply be passing the unopened box to you. If you need to pursue a warranty claim, you must go directly to Kahr.

Tuning or other services on your drum could be discussed separately, should you desire such. It would appear that the average basic tune up would cost less than $25 + ammo ($11 a load), but this would be a case by case issue. I can not speak for Merle on this, only myself.

Limit. In an attempt to be fair, let’s limit this buy to three (3) drums per customer.

Time frame.Orders will be accepted until Monday 1/3/05, after that, this buy is closed.

Terms. An order is accepted when full payment in cash, check or money order is received. Sorry, no CC or PayPal. Orders will be shipped in the sequence they were received, first in, first out. The only thing that counts here is paper in hand, please don’t email and ask me hold you a place. Drums will be shipped until current supply is exhausted. If additional supplies are available, they will be brought in ASAP to fill all orders received. Personal checks will not be cashed unless there is stock to fill the order. If current supply is inadequate to fill all orders received, outstanding orders will be notified. All orders subject to price increases from shipping company’s or suppliers (there was already a $10 increase from Kahr in receiving this shipment).

Make checks payable to: Diamond K

Mail to:Diamond K1390 E. 7th St.Delta, CO 81416

Pricing. By averaging the shipping, the cost of each drum will be $199, delivered to your door in the lower 48 states. Subject to change without notice (nice lawyer speech, huh?). CO residents, add applicable sales tax

If you desire to have one of the test group, they are available for an additional $11 to cover the ammo used in testing. Email to check availability prior to sending your order. These are offered “as they are” with no further representation being made.

In Closing, I wish to acknowledge and thank Merle for his consultation on this endeavor, and those whose jobs have been delayed a few days by it’s execution; thanks to you all.

Thank you very much for taking the time to test and give a very objective view of these new drums. Like PhilOhio, I'm tempted to get one (especially since the price is definately right, including the tune up service you are offering) but I feel Phil's comments are spot on regarding Kahr's QC. I'm going to hold back and not get one based on the quality of at least the initial batch of drums. It's really a sad a quality product has not been put forth. They would sell like hot cakes (and maybe will anyway) if the quality was there.

Interests:Full time gunsmith who loves Thompsons, 35+ years experience.

Posted 22 December 2004 - 02:57 PM

Happy to be of service guys.

The test drums are all spoken for, sorry.

I have not checked the board since this morning and apparently some of you who posted a desire for a test drum will be disappointed, as I was working from e mils in determining who got them. If you did not get an e mail confirmation from me, then you did not get a test drum. I am sorry for any confusion.

*******

Phil, we all know and agree that the details should have been right from the factory, I hope they are someday, but this is now and we deal with what we have. While I respect your decision, I have to take exception to the main reason you give for making it.

The metal used for the body is not “Way To Soft”. The testing shows (if not conclusively) that it is very little softer that the two other parts tested and well within an expected standard for this type of formed part; nothing substandard here that I can see from the tests performed. If we tested 100 GI drums and 100 new Kahrs I bet the average wouldn’t differ by more than a point or two. We won’t know until we actually do it however, if we ever get the chance. This is not a concern to me.

I do not know, but believe that the cartridge aperture was purposely made as large as it is with an eye towards insuring reliable feeding. That was a mistake and points out the root of the problem with all things Kahr and Thompson; the guys making the decisions about this don’t understand things Thompson. Simple as that. FWIW

I cannot have them since I live in MA and they are post-ban. Does anyone think a 1980s WestHurley drum is worth more than this? Maybe there are people who would trade a 1980s drum for a new production Kahr. Unless the word is that the 1980s ones were better.

I, like Robert, live in one of those East coast states (N.Y.) where the 'nanny state commissars' think they know what is best for the subjects. Consequently, New York has its own assault weapon/large capacity magazine ban.

Considering new "L" Drums can be had off Sturmgewehr for $200.00, I really don't see how the term Group Buy applies. Normally, (As I have participated in many group buys in the past.) a Group Buy is just that. An individual getting what he wants at a discounted price by purchasing a large quantity, thus passing the discount on to fellow man. I would have figured the price would have been lower than $199.00........

for $199.00 you cant go wrong,10 years from now they will be 5 times this much.

Or, more likely, in 10 years, new ones will be $199, plus an inflation adjustment.

This isn't a one off production run never to be done again. i suspect they will make them until their orders are filled, then lay in a thousand for stock, then when thsoe are gone, they will make another run.